Sunless tanning, also called self-tanning, is the ability to impart a tan to fair or light skin without the use of sunlight. In order to achieve a tanned look or otherwise darken their skin, individuals can expose their skin to sunlight or a source of simulated sunlight, e.g., a solar simulator or ultraviolet lamps. For many individuals, such exposure will stimulate formation of new melanin pigment and the retention of increased amount of melanin in the epidermis and produce a darkened skin color. However, some individuals find that such exposure does not produce the desired melanin formation and as a result the desired tan is not obtained. It is also well known that, as light skin humans age, the ability to produce melanin through ultraviolet light stimulation diminishes significantly. Exposure to the sun or a source of ultraviolet radiation can have deleterious effects for many individuals and can, in fact, cause sunburn, skin blistering, premature skin aging or skin cancer. Self-tanning or sunless tanning compositions offer a safe alternative and enable these individuals to obtain the desired tanned look.
Commercial formulations, using dihydroxyacetone [DHA], or DHA in combination with other reducing sugars such as 1,3,4-trihydroxy-2-butanone (erythrulose), applied locally to the skin, were developed for this purpose. Typical sunless tanning preparations sold to the consumer are in the form of a cream, lotion, gel or aerosol foam or spray. Additionally, within the last few years, indoor tanning salons have begun to offer automated sunless tanning spray applications as a safe alternative to UV tanning beds. These sunless tanning sprays are applied either in an enclosed booth or with a hand-held spray apparatus and involve the pressurized application of a sunless tanning solution containing DHA or combinations of DHA and erythrulose and are typically delivered over the entire body in the form of a mist.
Sunless tanning booth operations and automated spray systems for coating human skin with various cosmetic compositions including self-tanning compositions are known to the art.
The sunless tanning solutions used in these automated sunless tanning spray systems utilize relatively high levels of DHA (7-12%) versus the typical packaged sunless tanning creams, lotions, foams and sprays (3-7% DHA) sold in various retail outlets. Moreover, the automated sunless tanning spray systems deliver a mist of several ounces of sunless tanning solution in one misting session; much more sunless tanning product than typically would be self-applied by a consumer of a packaged sunless tanning product in any single application.
Sunless tanning booth sprays can coat the entire body with a light mist in one minute or less. Hand-held automated sunless tanning sprays utilizing an airbrush technique require several minutes to cover large areas of exposed skin. These pressurized spray systems dry quickly and produce a natural-looking tan. The spray booth systems, in particular, avoid the need for a second person to apply a sunless tanning cream, lotion, or foam product to hard to reach areas of the body. The sunless tanning booth sprays and hand-held pressurized sprays are “simple” aqueous solutions of DHA without the need for oils, emulsifiers, surfactants, polymers, and other stabilizers that can result in greasiness, stickiness, and longer drying times. This fast drying characteristic of these sunless tanning automated misting systems can be an advantage over conventional sunless tanning creams, lotions, gels, and foams.
Complete drying of the sunless tanning formulation is necessary to avoid staining of clothing. Conventional sunless tanning products caution the consumer to wait 15 minutes or more until the sunless tanning product applied is completely dry before dressing or contact with clothing. Sunless tanning solutions applied via automated misting systems are dry within one-two minutes after application. Automated sunless tanning formulations contain water soluble ingredients, are oil-free and exhibit low viscosity (e.g, less than 200 cps). These characteristics are required not only to speed drying but to avoid clogging of the spray nozzles and to facilitate the misting process without excessive back pressure.
The malodor issues associated with the automated tanning sprays has been solved with the use of 1,2-pentylene glycol as described in the two co-pending applications of John McCook et al; Ser. No. 10/382,868 and Ser. No. 10/694,972, titled SUNLESS TANNING PRODUCTS AND PROCESSES. Commercial application of this sunless tanning technology has resulted in improved results—darker, more even and low odor or odorless formulations vs. conventional technology. However, a small number of users of the new sunless tanning formulation, estimated at less than 1%, have experienced occasional skin dryness during the winter season in North America. This skin dryness is characterized by an uneven, dry, or mottled appearance on certain areas of the arms or legs of users within 24 hours of product application. Although the improved self-tanning formulations described in co-pending application Ser. No. 10/694,972 contain 1,2-pentylene glycol and other glycols that have humectant or moisturizing properties, the moisturizing properties are insufficient for a small number of consumers prone to dry or very dry skin, manifested particularly in the winter months. A novel approach for solving this skin dryness issue has been discovered through the addition of lactate salts.